Blast furnace installations have been configured so as to be capable of producing pig iron from iron ore by charging a starting material such as iron ore, limestone, or coke from the top of the blast furnace main body into the interior and blowing hot air and blast furnace blow-in coal (pulverized coal) as auxiliary fuel from a tuyere on the bottom side on the side of a blast furnace main body.
To stably operate the above blast furnace installation, the blast furnace blow-in coal must suppress accretion of blast furnace blow-in ash or occlusion by that blast furnace blow-in ash in a pathway leading to the tuyere of the blast furnace main body.
For example, it has been proposed to improve combustibility of blast furnace blow-in coal by adding a CaO-based flux such as limestone or serpentinite to pulverized coal of which the softening point of the pulverized coal ash is less than 1300° C., thereby adjusting the softening point of the ash in the pulverized coal to higher than or equal to 1300° C., and then blowing only the pulverized coal of which the softening point of the pulverized coal ash is higher than or equal to 1300° C. into the interior from a tuyere of a blast furnace main body (for example, refer to Patent Document 1 below).
Furthermore, a blast furnace operating method has been proposed, wherein, for example, any one or two or more types of CaO-based, MgO-based and SiO2-based flux are blown into the interior of a blast furnace from a tuyere (for example, refer to Patent Document 2 below).